Generators Arrrgg

nigtomdaw · December 2007

Hi I have a SW3024E and have had mixed results with various generators but I think I'm seeing a pattern emerge.

1 st Generator is a Kipor Suitcase Type Inverter Model rated at 1600 watts. I can set the SW3024E to 4.5 amps charge and 6 amps max AC in and it connects first time and runs delivering its rated power. Without problems. This is my back up back up genset.

2.nd Kipor Diesel 4500 watts.AVR alternator and again I could set the SW at 13 amps charge and 17 amps max AC and it also connected first time and delivered its rated power without fuss, till the Alternator went south at 500 hours!

3 rd A Chinese Honda Clone LPG unit rated at 6000 watts. This again delivered its rated power with the SW set up correctly but has issues syncing at times as off load the unit revs a little high but under load revs drop a little then gets close to 50 hz and 230 volts. at full load. This is my current unit.

The above three do or did as I expected but the next three units I am going to mention I have issues with.:grr

They are all original Honda's two x 2.2 kw 5.5hp and 1 x 6.5 hp 3.2 kw open frame site style units
These are branded units in GWO and each manages to deliver its rated power when connected to appliances direct. However when hooked up to the SW3024E I have to set the Max Charge and Max AC setting to less that half there rated values in order for the SW to keep from dropping them.

These small petrol 2.2 and 3.2 kw gennys are not liked at all by the SW even when I derate the settings below 50 % of the rated values. :grr

nigtomdaw · January 2008

Re: Generators Arrrgg

I supppose I didnt get a reply because I didnt really ask a question, so Ive read other threads on here and at OB & X and Im trying to understand about PF power correction factor and the inductive load requirements of the Inverter Charger versus the resistive loading that ic engined generators seem to be rated at.

Please butt in when I cock this up boys and girls.

Test carried out by Jim and others show that OB and assuming SW inverter chargers have a poorer PF rating when charging at low AC input charging figures as low as o.5 pf against 0.9 pf closer to there max AC input charging rate.

Ill leave the new XW and Magnum energy inv-chg out of this as both boast PF corrected charging circuits.

So this goes someway to demonstrate my results. My largest lpg genset is rated at 6 kw... 24 amps at 230 v and copes well at 12 amps ac charge max and 18 amps AC2 in max. Similar with the 4.5 kva avr based kipor diesel. slightly lower figures but again performed as expected.

The Kipor Inverter type 1600 watt as similar to the Honda EU inverter units and seems to deliver without fuss the rated value and wave form that both OB and SW units seem to like. on which everyone agrees Inverter gennys are good economical and do what they say on the tin !

Then we come to the three standard Honda Units 2 x 2.2kw and 1 x 3.2 kw. These units even down rated well below 50 % of there rated power are being dropped by the SW. They dont seem to rev or govern up as the SW wants more power.and the SW spits them out. They all govern correctly with power tools ?

Am I right in suspecting two things are causing this, at the low end of ac input for charging purposes the OB and SW pf drops to around 0.6 is suspect number one and the fact that these inverter chargers like to take the peak of the sine wave ie ac max peak voltage to charge effectively in DC being the second suspect ?

Q1.So what can I do to improve these small Hondas

A Add a resisitive load such as a 300 -500w halogen light to the genny
B.Wire in a capacitor across the live and neutral on genset ac out as Xantrex suggest

C Your solution if there is one.

Q2. Im looking for a perfect genset to complete my set up I will have 4 kw solar up this year and a 1KW wind turbine. Running with 1.6 kw for most of 2007 I reckon with 4 kw Ill only need 2-2.5 hours sun a day to meet my load requirement so I guesstimate around that 50 -75 hours genny runtime at 80 amps per year will cover those grey overcast still days.

Do I go for a Diesel 8-10kw 1500 rpm quality unit Im currently looking at a 3 cylinder Mitsubushi water cooled around $7k

Or a 11.5 kw ex mod 1500 rpm Lister Petter aircooled ? $3k

Or go for a Inverter based Honda EU unit around 3-5 kw ? around $1000 - $2500

Apart from stick welding my 3.2 kw inverter is fine for all my household needs

BB. · January 2008

Re: Generators Arrrgg

Here is a quick explanation of what a power factor corrected supply is/does (PDF File).

I dislike the idea of adding a 500 watt light to burn of electrons to just correct the power factor of the Non-PFC battery charger.

I tend to doubt that adding a capacitor across the power supply input would help anything as a non-PFC power supply typically has a very non-linear, narrow, current spike.

Without the hardware, a scope, current probe, and loads--I probably am out of my depth to help you much... Larger gensets, and different vendors/designs may handle the non-linear current loads better than others (as you have found). Getting PFC supplies is obviously the best solution (probably just disable the internal charger in the inverter and purchase a separate PFC battery charger).

-Bill

niel · January 2008

Re: Generators Arrrgg

if it is a case of being able to use the generators in question or not then try the incandescent light bulb idea, but try it at a smaller wattage and work your way up some. i think 500w in light bulbs is way too much and will load down the generator enough to take power away from the item you are trying to sent power to in the first place meaning there is a limit to the effectiveness of this method.

GreenerPower · January 2008

Re: Generators Arrrgg

nigtomdaw wrote: »

...Test carried out by Jim and others show that OB and assuming SW inverter chargers have a poorer PF rating when charging at low AC input charging figures as low as o.5 pf against 0.9 pf closer to there max AC input charging rate.

If you follow the OB thread on this, according to Sparky, the SW has PF corrected charger.

...Then we come to the three standard Honda Units 2 x 2.2kw and 1 x 3.2 kw. These units even down rated well below 50 % of there rated power are being dropped by the SW. They dont seem to rev or govern up as the SW wants more power.and the SW spits them out. They all govern correctly with power tools ?

Poor PF on the charger (as well as common AC-DC power supplies) is much worst than the power tools. The rectifier diodes inside the charger's circuitry just heavily loaded the the genny at the peaks of the sine waveform and this makes it's harder for the motor to govern the speed.

Q1.So what can I do to improve these small Hondas

A Add a resisitive load such as a 300 -500w halogen light to the genny
B.Wire in a capacitor across the live and neutral on genset ac out as Xantrex suggest

C Your solution if there is one.

The rectifiers/caps in the charger make it capacitive. But I doubt any external inductive load would help due to the peak loads on the waveform of the charger. My solution is to use a good PF-corrected 240VAC-60 VDC power supply to charge the battery directly. You can get it for $100 at wierdstuff.com (I posted info on this on the OB site).

... I guesstimate around that 50 -75 hours genny runtime at 80 amps per year will cover those grey overcast still days.

80 amps - is this 120V or 240V AC amps or battery DC amps ?

Q2. Im looking for a perfect genset to complete my set up I will have 4 kw solar up this year and a 1KW wind turbine. Running with 1.6 kw for most of 2007 I reckon with 4 kw Ill only need 2-2.5 hours sun a day to meet my load requirement so I guesstimate around that 50 -75 hours genny runtime at 80 amps per year will cover those grey overcast still days.

Do I go for a Diesel 8-10kw 1500 rpm quality unit Im currently looking at a 3 cylinder Mitsubushi water cooled around $7k

Or a 11.5 kw ex mod 1500 rpm Lister Petter aircooled ? $3k

Or go for a Inverter based Honda EU unit around 3-5 kw ? around $1000 - $2500

You are listing ~10KW models, so I assume 80A @ 120VAC. For that small amount of time a year on the gennie, I would use a cheap one IMHO.
GP

nigtomdaw · January 2008

Re: Generators Arrrgg

Sorry Im european spec 230 v 50hz the 80 amps is DC current I put into the batteries with about 12 amps AC infrom the genset . Im not aware that the SW is pfc the new XW units are they make note of it in the advertising blurb as do Magnum energy on all of there units. Ive never seen X SW advertise this feature but I will stand corrected.

Vic · January 2008

Re: Generators Arrrgg

Hi Nigel,

System sizing has always been the most thorny problem for me.

This winter, as have moved into my small cabin, with 120 VAC refer, blower on the wood stove and larger TV set going etc have needed to run a generator some days to charge the batteries. The recently acquired Honda EU-6500isa inverter generator does get upset with the stacked 5548 SW+'s. The problem is more pronounced as the charge current tapers off, just as you note, but still happens frequently at higher charge current, too. The largest problem seems to be that each inverter/charger works independantly of the other, and as one charger takes a gulp of AC current, it can upset the output of the other leg of the generator, making that leg go over voltage -- causing the inverter to drop it. After 10 or so seconds, the inverter tries again, and usually the other leg gets dropped the following time, and so on.

Have not tried to fine tune the settings in the nverters too much, but switching the generator to all output on one leg (120 VAC output) seems to reduce this problem, but then am losing 75 ADC of potential charge current. Have tried taking the generator out of the EcoThrottle mode, and that does nothing to solve this prob.

I do need to try tweaking the AC settings on the SW's, but this has not been a satisfying battery charging experience.

A neighbor has a system very much like mine -- stacked 5548 SW's, etc. His larger Honda Industrial genset. 20 HP motor, rated @ 9500 Watts continous, it seems to do just fine charging his batteries from both inverter/chargers at about 120 ADC or better. So it may take a real alternator with subasantial guts to do the job.

My "solution" was to spec a larger Diesel generator, which should fill all the current/future requirements. Is switchable to 3-phase as well and is rated @ 25KVA?20 KW. Even this genset has a disclaimer about powering inverters, saying something about derating iverter loads to 40% of the genset capacitty -- was translated from Japaneese, so may have lost something in the process. This genset seems large, but will loose 10 % due to altitude, and so on, so may not be such overkill. It is a quiet Kubota, and is fairly fuel-efficient at partial loads, and has a real alternator. That is my solution -- have not tried it yet, tho ... Never know what issues it will bring to the table, other than needing to deal with acquiring/dispensing fuel etc.

So good Luck with this issue, All the Best for ths New Year. Vic

nigtomdaw · January 2008

Re: Generators Arrrgg

Hi Vic seasonal greetings, i think quite a lot of people have problems with gensets whether X or OB. Your slightly different to me in having wo inverers but being able to use 2 legs off the genny. Where as Im soley 230 AC and only have one inverter.

As per my original post my larger gennys seem to cope and the smaller inverter type have no problems delivering rated power. its those smaller in between site style gennys that are bordering on hopeless. Bear in mind your system inverters are 3 times bigger that mine 3.2 kw vrs 11 kw

I know that by the time all my solar is up for 8-10 months of the year Ill be fine, but this years winter has been wet and cold and my mains agricultural water supplies went down for service which means using a pressure pump which rated a 1000w + surge throws a spanner in the works when you set your SW to extract the most from your genny. Plus having double our normal occupancy with guest for Xmas faffing about with inverters and generators having continual tiffs and splits gets tiresome. Im serioulsy looking at a ex MOD 11.75 kva twin cylinder Lister Petter again serious over kill but it has 3 phase and as I probably will never need more that 6000 watts to cover max house loads and max charging loads then this may be the price. Its way cheaper than a Honda 6 kw inverter style unit.

I dont really want to go down the separate charger route but I can clearly see its merits in the real world. Im going to also look at some of the smaller direct DC generators that are available at 28 volt from our telecoms industry and ex mod also.

Nice to here from you Vic

Ralph Day · January 2008

Re: Generators Arrrgg

Vic
Here's the best lesson from an elec engineer off-grid friend of mine regarding de-rating generators under rectified loads (charging).

Ralph

The current in an AC rectfier circuit feeding a battery conducts only when the voltage of the output exceeds the voltage of the battery or capacitor. So say you are charging your battery at 50 volts. The unloaded AC voltage peak is likely 55 volts. The AC voltage wave cycle increases from zero to 50.7 volts (the battery voltage plus the drop across the diode) without any current flowing (nada). Then at 51 volts, the battery looks like a virtual short circuit and current starts flowing like crazy until the AC voltage wave drops below 51 volts again at which point as it continues through the cycle and the current promptly drops to zero. The whole thing then repeats itself with the next wave. The current has only flowed for maybe 15% of the total cycle and has done so in a nasty sharp spike, not a sine wave. When you take the average value of the current, it may read some resonable value - say 60 amps. But when the current spike was there, the current value may have peaked at 150 amps or more depending upon the internal resistance of the battery, the line resisitance, the internal resistance of the generator, the internal resistance of the charger and the diode drops in the charger. During conduction then, the losses in the system (current squared times the resistance) could be 4 or 5 times what a circuit with a pleasant current sine wave might be. To help aleviate this problem, we oversize the conductors and run the voltage a little high.

I have run my 10kw diesel unit at 7 kw (or maybe a little more when the ambient temp is cold), and never had a thermal cut-out. I have a sw4048 and a lift truck charger, which when run at the same time can (and once did) overload the genset such that it shut down. That was in the summer, and at the time i didn't have an RMS meter to really know what i was loading the genset to.

Running stacked 5548"s i don't doubt you could overload a 10kw unit but not a 20kw. The "hunting" that sw unit do when charging has not been fully explained to me yet. Xantrex service said it's just the nature of the beasts. With two units hunting at the same time, it's easy to see you could get drops happening. Hopfully your 20kw unit won't have to wrestle with the chargers.

For those uninitiated "hunting" is when you are charging, and the unit will vary several amps up or down from your setpoint...25amp setpoint may see 23-28amps charging, up and down. Usually happens during bulk/absorb when charger is working hard.

ralph

Vic · January 2008

Re: Generators Arrrgg

Hi Ralph,

Thanks for the well-reasoned reply. Do have an engineering background ... profession was as a EE, so do generally agree with your descriptoon of the process of charging, at least from a transformer/rectifier power supply. Do not really know what is behind the skins of the 5548's.

Have used a Brute-Force charger to charge an exact duplicate of the battery bank in question via a Honda inverter generator. That was a 60 Hz transformer/bridge rectifier/capacitor filter (no inductor in filter). Used a Variac as the current control ... generator was quite happy. Have also used this power Supply into an MX-60 CC, and all was happy. So, the inverters are screwing around and causing much larger current peaks on the AC in than would a simple Brute Focce PS. This PS only has a 50 Amp rated transformer, and was hoping to get in excess of 75 Amp charge current from the stacked inverter, in order to approach C/20 on occasion for battery health. Not the world's end, but just a disappointing reality. And a whine. It does seem that a single inverter charging from the generator solves the problem of one inverter dropping its leg in repeating cycles.

Will attenpt to do some actual measurements to more accurately describe the sequence of events ... do not have a good current probe for the scope, nor a digital/storage scope, or even a 4-channel analog scope, so my abilities at this point are limited.

AND while at the off-grid location, am without internet ... so will be mute until next week.

Thanks again, Ralph for the info. Happy charging to all for 2008 Vic

westbranch · January 2008

Re: Generators Arrrgg

hello all that have been laying out their nightmares re 'dropping' etc.

Being a relative newbee to this field can someone please explain "stacked" , which has several connotations... most of which go back to my youth..

Am I right in that that the problem comes into play when one gets into the >= 1 kw installations (with parallel battery banks?) Is this only seen in 24 & 48v + banks? at high amperage?

thanks

Eric

Brock · January 2008

Re: Generators Arrrgg

I could be wrong but I believe the term "stacking" came from Trace (now Xantrex). It usually refers to connecting two 120vac inverters in a way to give you 240vac keeping the two inverters in sync with each other with each inverter supplying one side of the 240vac. I have seen the term stacking now used in connecting multiple inverter together even in a parallel configuration.

So stacking SW5548 would give you 11kw at 240vac, with each 120vac leg being able to supply 5.5kw. If you ran them in parallel they would supply 11kw all on one side at 120vac and not output 240vac.

I don't think the problem is limited to larger inverter or higher voltage battery bank just how much power you are trying to put back in the batteries compared to the genset. So say you have a 500w inverter/charger and a 500w genset you would likely have problems. So with larger systems you are just more likely to have inverter matched or even larger then the gensets powering them. For instance I have stacked SW2512's, so I have two 2.5kw 12v inverters set up to supply 240vac from a 12v battery bank. The two gensets I have are a 1.2 kw cheep portable genset and 2.4kw kohler unit. I ended up getting two 120vac 55 amp chargers and just power those from the gensets and charge the battery directly to avoid these problems.

nigtomdaw · January 2008

Re: Generators Arrrgg

From my expierience over this last year excluding Inverter style gen-sets which seem to give you what that say they will and thus you can set your Inverter AC in and DC Charging values accordingly then I think for ordinary bread and butter gensets you will avoid problems if you use the following formula.

Take Inverter Power Rating as = P (Mine is 3300 watts)
Take Max Charging Capacity = C (Mine is 24 v x 100 amps =2400 watts)

My formula would then be P + (C x 2) = Absolute Minimum Generator Size

To give an off grid home no fuss no hassle no drop max charge capability for said inverter. (excludes the newer PFC Inverter Chargers from Magnum and Xantrex

So in my case 3300 + (2400x2) = 8100 watts

So I reckon Ill need a minimum of a 10 kva 240 v 50 hz gen to solve all my genset problems and allow max charging with out worry.

Just my theory but I bet its close !;)

System2 · January 2008

Re: Generators Arrrgg

Nigel,

pardon me.... butting in!

nigtomdaw wrote: »

Please butt in when I cock this up boys and girls.

Is it me? or is it just plain uncomfortable to hear the words cock and butt in the same sentence?

nigtomdaw wrote: »

Do I go for a Diesel 8-10kw 1500 rpm quality unit Im currently looking at a 3 cylinder Mitsubushi water cooled around $7k

Or a 11.5 kw ex mod 1500 rpm Lister Petter aircooled ? $3k

Or go for a Inverter based Honda EU unit around 3-5 kw ? around $1000 - $2500

.

So, it seems that the SW series might have issues with AC power supply? So if that is true? then is it still a no brainer to go with an SW over a Tripp Lite? ie: when using generators?

Kevin

nigtomdaw · January 2008

Re: Generators Arrrgg

Outback and X all have issues with undersized gensets, its part of there design and what part of the sinewave they use for charging. Magnum and the new XW all use power factor corrected charging circuits which is a plus as they use less genny power and give better charging....time goes on things improve. The SW is at the end of its production run hence the new XW units. Going for your Tripplite is your decision I assume its cheap and may serve your needs but then living with it is your choice I saw one the other month smoke 2 new electronic water pumps buyer beware !. Running a genny when living in the quiet country side is a pain in the b..t and I want to run it for the least time possible without syncing problems with out dropping in and out every time a largish load like a water pump kicks in. So hence my little formula . If it helps it helps, by the way I think Butt has several meanings in the UK where as you use fanny for one thing and its meaning in the UK is totally different.

PS Currently using a 6kw LPG generator I get by charging around 80 amps (Approx 2kw of power but it draws 2.5-2.7 kw from the genny to achieve it ) it takes about 3 hours solid running to put my batteries from 90 % to fully charged, it allows us to run the house with fridge freezer , TV and washing machine going , however as like now with my mains water off line we have to use a 1000 watt pump and this is enough to throw out the genny sometimes when the fridge freezer clicks on at the same time. The SW3024E at 3.3 kw can handle these on its own without problems . So for my use a 8kw (10kva) would be better . So my formula is tailored to a family Living off grid with all mod cons except no air con just ceiling fans , cooking on gas and wood burner. You would be surprise how often the fridge freezer kicks in when the water pumps going doing a wash Murphys Law?

System2 · January 2008

Re: Generators Arrrgg

Hi Nigel,

yeah.....it helps when we keep genset operation to a minimum (ie to keep the peace and quite and to not spoil the ether) so.... that is why I want to charge my batteries as efficiently and effectively and quietly as possible.

Now, whilst you are able to (fanny) about and are able set up several gen sets and monitor each ones performance under load conditions some of us might not have that same luxury!
ie; I only have one genset (and one chance) to get it right!

So powerfactor is one thing to consider.....

I will use your formula to source out a charger that fits my AC power supply and DC battery needs!

X and OB have the name? but I wonder if there are other options like purchasing an independent power corrected batt charger and then purchasing a Dc to Ac inverter separately?

Anyone?

nigtomdaw · January 2008

Re: Generators Arrrgg

EV2007 Im only passing on my exps Im pissed at the efficiency of my batt chrg efff of the SW but I also like my SW. So Ive made my investment and I have 2 cut my cloth accordingly. In a couple of days my 1.6 kw array will be 2.4 kw which IMHO will increase my charging capacity by 50 % ie the first 800w takes the standing losses leaves 800 w for real batt charging thus my new 800 watts will make a big 50 % asset toward completeing 2 hours of float charge,,,, Im out in the real off grid world and like Vic u have to fire up the hydro carbon munching gent at some stage so whist I enjoy our conversation Im doing it and your planning it. Buy mod sine wave and pass out more bucks when u learn your lesson....SW was a RE icon I bought 2 years ago after installing a C40 which worked as it should so I went back 2 the same company for my inverter,with my bucket of hindsight I may have gone down the OB route but they have as many if not more Gen issues than X , Magnum offer a cross the range mod or pure sign wave inv -chrg units all boast I think PFC chargers,, Life is about choices I dont regret my SW decision a fantastic piece of kit I doubt anyone will dissagree, I have 2 x 3048E OB units at my home for sale but ther problem is you need ac dc add on boxes a lcd display and a hub and monitor on the plus side u only need one BTS where I have four X units, 2 x c40.s 1 x SW3024E and 1 x XBM . EV 2007 at some stage u have 2 take a dive and get your hair wet, Ive made a few mistakes.. but none that I cant afford. Love the forum learning all the time. Nigel UK birth Spain by Location !

icarus · January 2008

Re: Generators Arrrgg

nigel writes:

"You would be surprise how often the fridge freezer kicks in when the water pumps going doing a wash Murphys Law?"

Just a thought, can't you relay control either the pump washing machine or freezer so that only on can run at a time? Of course you would use the same load over time, but your peak load would be less.

Icarus

Generators Arrrgg

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